Structures - Monica

Describe the structure of and bonding in silicon and silicon dioxide

Structure of silicon:
Number of electrons: 14
Electron configuration: 2,8,4

Form a face-centered diamond cubic crystal structure.



Bonding in silicon:
Has four bonding electrons, like carbon - gives it ability to combine with other elements or compounds.

Structure of silicon dioxide:
4 Oxygen atoms surrounding a central silicon atom
Tetrahedral

Bonding in silicon dioxide:
Covalent bonds

α-quartz	rhombohedral (trigonal) hP9, P3121 No.152[12[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-11|]]]	Helical chains making individual single crystals optically active; α-quartz converts to β-quartz at 846 K	A-quartz.png
β-quartz	hexagonal hP18, P6222, No.180[13[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-12|]]]	closely related to α-quartz (with an Si-O-Si angle of 155°) and optically active; β-quartz converts to β-tridymite at 1140 K	B-quartz.png
α-tridymite	orthorhombic oS24, C2221, No.20[14[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-trid-13|]]]	metastable form under normal pressure	A-tridymite.png
β-tridymite	hexagonal hP12, P63/mmc, No. 194[14[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-trid-13|]]]	closely related to α-tridymite; β-tridymite converts to β-cristobalite at 2010 K	B-tridymite.png
α-cristobalite	tetragonal tP12, P41212, No. 92[15[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-14|]]]	metastable form under normal pressure	A-cristobalite.png
β-cristobalite	cubic cF104, Fd3m, No.227[16[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-15|]]]	closely related to α-cristobalite; melts at 1978 K	B-cristobalite.png
faujasite	cubic cF576, Fd3m, No.227[17[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-16|]]]	sodalite cages connected by hexagonal prisms; 12-membered ring pore opening; faujasite structure.[9[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-fau-8|]]]	Faujasite structure.svg
melanophlogite	cubic (cP*, P4232, No.208)[4[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-mel-3|]]] or tetragonal (P42/nbc)[18[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-17|]]]	Si5O10, Si6O12 rings; mineral always found with hydrocarbons in interstitial spaces-a clathrasil[19[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-18|]]]	MelanophlogiteStucture.png
keatite	tetragonal tP36, P41212, No. 92[20[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-19|]]]	Si5O10, Si4O14, Si8O16 rings; synthesised from glassy silica and alkali at 600–900K and 40–400 MPa	Keatite.png
moganite	monoclinic mS46, C2/c, No.15[21[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-20|]]]	Si4O8 and Si6O12 rings	Moganite.png
coesite	monoclinic mS48, C2/c, No.15[22[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-21|]]]	Si4O8 and Si8O16 rings; 900 K and 3–3.5 GPa	Coesite.png
stishovite	Tetragonal tP6, P42/mnm, No.136[23[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-22|]]]	One of the densest (together with seifertite) polymorphs of silica; rutile-like with 6-fold coordinated Si; 7.5–8.5 GPa	Stishovite.png
poststishovite	orthorhombic oP12, Pnc2, No.30[24[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-23|]]]		Poststishovite.png
fibrous	orthorhombic oI12, Ibam, No.72[25[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-24|]]]	like SiS2 consisting of edge sharing chains	SiS2typeSilica.png
seifertite	orthorhombic oP, Pbcn[26[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-25|]]]	One of the densest (together with stishovite) polymorphs of silica; is produced at pressures above 40 GPa.[27[[http://en.wikipedia.org/wiki/Silicon_dioxide#cite_note-26|]]]	SeifertiteStructure.png